Module tuple | Tarantool
Reference C API reference Module tuple

Module tuple

type box_tuple_format_t
box_tuple_format_t *box_tuple_format_default(void)

Tuple format.

Each Tuple has an associated format (class). Default format is used to create tuples which are not attached to any particular space.

type box_tuple_t

Tuple

box_tuple_t *box_tuple_new(box_tuple_format_t *format, const char *tuple, const char *tuple_end)

Allocate and initialize a new tuple from raw MsgPack Array data.

Parameters:
  • format (box_tuple_format_t*) – tuple format. Use box_tuple_format_default() to create space-independent tuple.
  • tuple (const char*) – tuple data in MsgPack Array format ([field1, field2, …])
  • tuple_end (const char*) – the end of data
Returns:

NULL on out of memory

Returns:

tuple otherwise

See also: box.tuple.new()

Warning

When working with tuples, it is the developer’s responsibility to ensure that enough space is allocated, taking especial caution when writing to them with msgpuck functions such as mp_encode_array().

int box_tuple_ref(box_tuple_t *tuple)

Increase the reference counter of tuple.

Tuples are reference counted. All functions that return tuples guarantee that the last returned tuple is reference counted internally until the next call to API function that yields or returns another tuple.

You should increase the reference counter before taking tuples for long processing in your code. The Lua garbage collector will not destroy a tuple that has references, even if another fiber removes them from a space. After processing, decrement the reference counter using box_tuple_unref(), otherwise the tuple will leak.

Parameters:
Returns:

-1 on error

Returns:

0 otherwise

See also: box_tuple_unref()

void box_tuple_unref(box_tuple_t *tuple)

Decrease the reference counter of tuple.

Parameters:

See also: box_tuple_ref()

uint32_t box_tuple_field_count(const box_tuple_t *tuple)

Return the number of fields in a tuple (the size of MsgPack Array).

Parameters:
size_t box_tuple_bsize(const box_tuple_t *tuple)

Return the number of bytes used to store internal tuple data (MsgPack Array).

Parameters:
ssize_t box_tuple_to_buf(const box_tuple_t *tuple, char *buf, size_t size)

Dump raw MsgPack data to the memory buffer buf of size size.

Store tuple fields in the memory buffer.

Upon successful return, the function returns the number of bytes written. If buffer size is not enough then the return value is the number of bytes which would have been written if enough space had been available.

Returns:-1 on error
Returns:number of bytes written on success.
box_tuple_format_t *box_tuple_format(const box_tuple_t *tuple)

Return the associated format.

Parameters:
Returns:

tuple format

const char *box_tuple_field(const box_tuple_t *tuple, uint32_t field_id)

Return the raw tuple field in MsgPack format. The result is a pointer to raw MessagePack data which can be decoded with mp_decode functions, for an example see the tutorial program read.c.

The buffer is valid until the next call to a box_tuple_* function.

Parameters:
  • tuple (box_tuple_t*) – a tuple
  • field_id (uint32_t) – zero-based index in MsgPack array.
Returns:

NULL if i >= box_tuple_field_count()

Returns:

msgpack otherwise

enum field_type
enumerator ::FIELD_TYPE_ANY
enumerator ::FIELD_TYPE_UNSIGNED
enumerator ::FIELD_TYPE_STRING
enumerator ::FIELD_TYPE_NUMBER
enumerator ::FIELD_TYPE_DOUBLE
enumerator ::FIELD_TYPE_INTEGER
enumerator ::FIELD_TYPE_BOOLEAN
enumerator ::FIELD_TYPE_VARBINARY
enumerator ::FIELD_TYPE_SCALAR
enumerator ::FIELD_TYPE_DECIMAL
enumerator ::FIELD_TYPE_ARRAY
enumerator ::FIELD_TYPE_MAX

Possible data types for tuple fields.

One cannot use STRS/ENUM macros for types because there is a mismatch between enum name (STRING) and type name literal (“STR”). STR is already used as a type in Objective C.

type box_key_def_t

Key definition

box_key_def_t *box_key_def_new(uint32_t *fields, uint32_t *types, uint32_t part_count)

Create a key definition with the key fields with passed types on passed positions.

May be used for tuple format creation and/or tuple comparison.

Parameters:
  • fields (uint32_t*) – array with key field identifiers
  • types (uint32_t) – array with key field types
  • part_count (uint32_t) – the number of key fields
Returns:

key definition on success

Returns:

NULL on error

void box_key_def_delete(box_key_def_t *key_def)

Delete a key definition

Parameters:
box_tuple_format_t *box_tuple_format_new(struct key_def *keys, uint16_t key_count)

Return new in-memory tuple format based on passed key definitions

Parameters:
  • keys (key_def) – array of keys defined for the format
  • key_count (uint16_t) – count of keys
Returns:

new tuple format on success

Returns:

NULL on error

void box_tuple_format_ref(box_tuple_format_t *format)

Increment tuple format reference count

Parameters:
void box_tuple_format_unref(box_tuple_format_t *format)

Decrement tuple format reference count

Parameters:
int box_tuple_compare(const box_tuple_t *tuple_a, const box_tuple_t *tuple_b, const box_key_def_t *key_def)

Compare tuples using key definition

Parameters:
Returns:

0 if key_fields(tuple_a) == key_fields(tuple_b)

Returns:

<0 if key_fields(tuple_a) < key_fields(tuple_b)

Returns:

>0 if key_fields(tuple_a) > key_fields(tuple_b)

See also: enum field_type

int box_tuple_compare_with_key(const box_tuple_t *tuple, const char *key, const box_key_def_t *key_def);

Compare a tuple with a key using key definition

Parameters:
  • tuple (const box_tuple_t*) – tuple
  • key (const char*) – key with MessagePack array header
  • key_def (const box_key_def_t*) – key definition
Returns:

0 if key_fields(tuple) == parts(key)

Returns:

<0 if key_fields(tuple) < parts(key)

Returns:

>0 if key_fields(tuple) > parts(key)

See also: enum field_type

type box_tuple_iterator_t

Tuple iterator

box_tuple_iterator_t *box_tuple_iterator(box_tuple_t *tuple)

Allocate and initialize a new tuple iterator. The tuple iterator allows iterating over fields at the root level of a MsgPack array.

Example:

box_tuple_iterator_t* it = box_tuple_iterator(tuple);
if (it == NULL) {
    // error handling using box_error_last()
}
const char* field;
while (field = box_tuple_next(it)) {
    // process raw MsgPack data
}

// rewind the iterator to the first position
box_tuple_rewind(it)
assert(box_tuple_position(it) == 0);

// rewind three fields
field = box_tuple_seek(it, 3);
assert(box_tuple_position(it) == 4);

box_iterator_free(it);
void box_tuple_iterator_free(box_tuple_iterator_t *it)

Destroy and free tuple iterator

uint32_t box_tuple_position(box_tuple_iterator_t *it)

Return zero-based next position in iterator. That is, this function returnы the field id of the field that will be returned by the next call to box_tuple_next(). Returned value is zero after initialization or rewind and box_tuple_field_count() after the end of iteration.

Parameters:
Returns:

position

void box_tuple_rewind(box_tuple_iterator_t *it)

Rewind iterator to the initial position.

Parameters:

After: box_tuple_position(it) == 0

const char *box_tuple_seek(box_tuple_iterator_t *it, uint32_t field_no)

Seek the tuple iterator.

The result is a pointer to raw MessagePack data which can be decoded with mp_decode functions, for an example see the tutorial program read.c. The returned buffer is valid until the next call to box_tuple_* API. The requested field_no is returned by the next call to box_tuple_next(it).

Parameters:
  • it (box_tuple_iterator_t*) – a tuple iterator
  • field_no (uint32_t) – field number - zero-based position in MsgPack array

After:

  • box_tuple_position(it) == field_not if returned value is not NULL.
  • box_tuple_position(it) == box_tuple_field_count(tuple) if returned value is NULL.
const char *box_tuple_next(box_tuple_iterator_t *it)

Return the next tuple field from tuple iterator.

The result is a pointer to raw MessagePack data which can be decoded with mp_decode functions, for an example see the tutorial program read.c. The returned buffer is valid until next call to box_tuple_* API.

Parameters:
Returns:

NULL if there are no more fields

Returns:

MsgPack otherwise

Before: box_tuple_position() is zero-based ID of returned field.

After: box_tuple_position(it) == box_tuple_field_count(tuple) if returned value is NULL.

box_tuple_t *box_tuple_update(const box_tuple_t *tuple, const char *expr, const char *expr_end)
box_tuple_t *box_tuple_upsert(const box_tuple_t *tuple, const char *expr, const char *expr_end)
Found what you were looking for?
Feedback